1. Field of the Invention
This invention relates to axial flow, gas turbine engines and more specifically to a rotor assembly of such an engine.
2. Description of the Prior Art
In a gas turbine engine of the type referred to above, working medium gases are pressurized in a compressor section, burned with fuel in a combustion section and expanded through a turbine section. The flowpath for the working medium gases extends in an essentially axial direction. The working medium gases in the compressor and turbine sections flow alternatingly through rows of rotor blades and rows of stator vanes. Energy extracted from the rotor blades in the turbine section is mechanically carried to the rotor blades of the compressor section to enable pressurization of the incoming working medium.
A seal between each row of rotor blades and the adjacent rows of stator vanes is provided to prevent the leakage of working medium gases around the operative surfaces of the blades and vanes. At the inner diameter of the flowpath a seal, such as a labyrinth seal, is conventionally provided between each disk and blade assembly and the adjacent stationary structure by a first element extending from stationary structure and a second element extending of the disk and blade assembly. U.S. Pat. Nos. 2,945,671 to Petrie entitled "Bladed Rotor Constructions for Fluid Machines" and 3,703,808 to Sterns entitled "Turbine Blade Tip Cooling Air Expander" representatively illustrate such a labyrinth seal. Petrie shows the rotating seal element extending directly from the rotor disk; Sterns shows the rotating seal element extending from sideplates mechanically attached to the rotor disk at both the upstream and downstream sides thereof.
In modern gas turbine engines a collateral function of such seals within the turbine section is to confine rotor blade cooling air inwardly of the flowpath and to direct such cooling air to the rotor blades. Representative illustrations of turbine section structures include U.S. Pat. Nos. 3,635,586 to Kent et al entitled "Method and Apparatus for Turbine Blade Cooling"; 3,768,924 to Corsmeier et al entitled "Boltless Blade and Seal Retainer"; and 3,989,410 to Ferrari entitled "Labyrinth Seal System". In each of the above illustrated structures the rotating seal element extends from sideplates which are mechanically affixed to the respective rotor disks.
Mechanical attachment of the sideplates to the rotor disk and indeed the sideplates themselves add mechanical complexity to the rotor system. Effective rotor structures without the added mechanical complexity of sideplates are known to be desired. Two structures free of sideplates are illustrated in U.S. Pat. Nos. 3,437,313 to Moore entitled "Gas Turbine Blade Cooling" and 3,791,758 to Jenkinson entitled "Cooling of Turbine Blades". In both Moore and Jenkinson the rotating seal is formed of elements extending individually from each of the rotor blades. Neither the structural adequacy nor the sealing effectiveness of the above structures is known to the present patentee.
Notwithstanding knowledge of the above type structures, scientists and engineers in the gas turbine industry continually search for yet improved disk and blade structures.